1. Field of the Invention
The present invention relates to a discharge head which is provided with a discharge driving element and a printed circuit board or wired board connected thereto, and a method for producing the discharge head.
2. Description of the Related Art
As for the discharge head, for example, a liquid droplet discharge head (ink-jet head) is already known, which is provided for a liquid droplet discharge apparatus such as an ink-jet printer. The ink-jet head is provided with a plurality of pressure chambers, nozzles, and piezoelectric elements. The liquid is supplied from a liquid supply source to the pressure chambers. The volume of the pressure chambers is changed by deforming the piezoelectric elements each of which is arranged opposingly to one of the pressure chambers. Accordingly, the pressure is applied to the liquid contained in the pressure chambers, and the liquid is discharged from the nozzles connected to the pressure chambers.
Surface electrodes are formed on the piezoelectric elements so that the surface electrodes are opposed to the pressure chambers. The driving signal is applied to the surface electrodes by the aid of a circuit board or wired board such as a flexible wiring member. Accordingly, the electric field is applied to the piezoelectric elements to deform the piezoelectric elements. The wired board includes a wiring which transmits various signals such as the driving signal supplied from the apparatus to the discharge head via a driver IC, and terminals which correspond to the surface electrodes. The terminals are connected to the surface electrodes, respectively, and thus the driving signal is transmitted to the surface electrodes via the wired board.
In general, the terminals of the wired board and the connecting portions of the surface electrodes are connected to one another such that a conductive brazing material such as solder is allowed to intervene between the terminals of the wired board and the connecting portions of the surface electrodes, and the conductive brazing material is melted by being heated (see Japanese Patent Application Laid-open No. 7-156376, page 3, FIG. 10). On the other hand, the terminal and the connecting portion are connected to one another without the conductive brazing material in some cases as described in Japanese Patent Application Laid-open No. 8-156252 (page 3, FIG. 2). When the conductive brazing material is not used, a cutout portion, which has an areal size larger than that of each of the surface electrodes, is provided in a lower film of two stacked films possessed by a printed circuit board. Further, a terminal, which has an areal size smaller than that of each of the surface electrodes, is formed on the lower surface of the upper film disposed in the cutout portion. A conductive adhesive is applied dropwise to the surface of each of the surface electrodes, and then the terminals are pressurized against the surface electrodes. Accordingly, the terminals and the surface electrodes are electrically connected to one another. The connecting portions between the terminals and the surface electrodes are disposed at the positions opposed to the pressure chambers.